Dispensing devices permitting the delivery of products in the form of measured quantities are most often of complicated structure and require a notably high number of pieces such as balls, valves, springs, nozzles and the like.
There has been proposed, by FR-B-2 674 024 and FR-B-2 728 809, devices for dispensing measured quantities suitable for various contents and having a simple structure requiring few pieces.
In FR-B-2 674 024, the device for dispensing measured quantities is constituted by a resiliently deformable flexible member disposed in a rigid cap, this assembly being suitable for a container whose upper portion is of corresponding shape to receive it. When pressure is applied to the cap, a measured quantity of product is isolated and its dispensing is caused whilst producing the reproduction of an identical measured quantity within the assembly.
Thus, this assembly is constituted by this resiliently deformable internal member having an annular portion from which extends a cylindrical skirt defining, with the cap, a measured quantity chamber, the end of the cylindrical skirt of truncated conical shape resting against an annular internal flange of the cap. The internal resilient member also comprises a projection defining the bottom of the measured quantity chamber, mounted on the container, said projection being provided with an opening provided with a flat valve for communication with the interior of the receptacle. When pressure is exerted on the cap, the latter slides axially relative to the container and to the projection mounted on said container and the product enclosed within the measured quantity chamber is subjected to a pressure which closes the flap over the communication opening toward the interior volume of the receptacle and tends to exert a pressure on the walls of the measured quantity chamber. This pressure tends in particular to space the end of the cylindrical skirt from the internal member bearing on the flange of the cap by freeing a passage for the product toward an outlet opening in the cap, the truncated conical shape of the end of the cylindrical skirt facilitating this spacing.
In FR-B-2 728 809, the measured quantity dispensing device is constituted by a pushbutton incorporating a measured quantity chamber traversed centrally by a tube communicating with the outlet opening of the pushbutton and pierced radially at its lower end. This pushbutton is mounted on a suitable support on the neck of a receptacle and within which is mounted axially slidably this pushbutton. A piece of resiliently deformable material is interposed between the support and the pushbutton. This piece comprises an extensible tubular portion closed at its base and within which is emplaced the tube of the pushbutton whilst a peripheral collar of the piece extends over an annular portion of the support it having at least one opening facing the internal volume of the receptacle. The measured quantity chamber is defined between said piece and the pushbutton, the piece being in sealed bearing relationship against the pierced portion of the tube of the pushbutton. When a pressure is exerted on the pushbutton, the latter slides axially relative to the support and deforms the tubular portion of the intermediate piece, the volume of the measured quantity chamber decreases and the product is thus subjected to a pressure which spaces the tubular portion of the intermediate piece from the end of the pushbutton tube where is provided radially an opening. This spacing of the wall permits the evacuation of the product through the tube of the pushbutton in the direction of the outlet opening.
Although these devices have the advantage of requiring few pieces and are thus of an interesting cost, they however have a drawback. Thus, the resiliently deformable walls of the intermediate members act as springs between the support and the pushbutton so as to permit on the one hand the axial sliding of this latter toward a so-called active position of engaging the pushbutton on the support to decrease the internal volume of the measured quantity chamber and, on the other hand, returning said pushbutton to its initial rest position when pressure is no longer exerted on it. It is thus important that the resiliently deformable walls of the intermediate or internal member preserve their properties. However, these walls are principally in contact with the product to be dispensed and there can follow an alteration of the qualities and properties of the resiliently deformable material, leading to poor operation of the dispenser comprising such a dispensing device.